As a technology for achieving a high resolution by combining images, for example, there is a known method in which a plurality of images are captured by shifting an image sensor in a direction orthogonal to an optical axis, and those images are combined. A technology for suppressing artifacts, such as ghosts occurring in a region in which an imaging subject is moved, when a high-resolution image is acquired by using this method has been disclosed (for example, see Patent Literature 1).
With this technology, similarities among the plurality of images are calculated, and combining ratios among the images are controlled on the basis of the similarities. In other words, one of the plurality of captured images is used as a standard image, the rest of images are used as reference images, differences between the standard image and the reference images are calculated for individual regions, and the similarities between the two types of images are determined on the basis of the differences. Then, the combining ratios of the reference images are increased in regions in which the similarities are high, and the combining ratio of the standard image is increased in regions in which the similarities are low, thereby suppressing the occurrence of artifacts due to movement and position displacement of the imaging subject.